1. Field of the Invention
This invention relates to a recording medium such as a digital video disc, or a digital versatile disc (DVD). Also, this invention relates to an apparatus for encoding an audio signal. Furthermore, this invention relates to an apparatus for decoding an audio signal. In addition, this invention relates to an optical disc player such as a DVD (digital video disc) player.
2. Description of the Related Art
Optical discs for storing information include digital video discs (DVD""s). A standard DVD stores a combination of an audio signal and a video signal. The audio-signal recording capacity of the standard DVD is significantly smaller than the video-signal recording capacity thereof. It is difficult to manage time-related information of the audio signal recorded on the standard DVD. It is difficult to read out information of the titles of tunes represented by the audio signal recorded on the standard DVD.
It is a first object of this invention to provide an improved recording medium.
It is a second object of this invention to provide an improved apparatus for encoding an audio signal.
It is a third object of this invention to provide an improved apparatus for decoding an audio signal.
It is a fourth object of this invention to provide an improved optical disc player.
A first aspect of this invention provides a digital signal recording disc comprising a first area storing a first-channel digital audio signal and a second-channel digital audio signal, the first-channel digital audio signal resulting from quantizing a first-channel analog audio signal with a first quantization bit number, the second-channel digital audio signal resulting from quantizing a second-channel analog audio signal with a second quantization bit number; and a second area differing from the first area and storing information of the first and second quantization bit numbers.
A second aspect of this invention is based on the first aspect thereof, and provides a digital signal recording disc wherein the first-channel digital audio signal comprises a front-channel digital audio signal and the second channel digital audio signal comprises a rear-channel digital audio signal, and the first and second quantization bit numbers are different from each other.
A third aspect of this invention provides a digital signal recording disc comprising a first area storing a first-channel digital audio signal and a second-channel digital audio signal, the first-channel digital audio signal resulting from an analog-to-digital conversion of a first-channel analog audio signal at a first sampling frequency, the second-channel digital audio signal resulting from an analog-to-digital conversion of a second-channel analog audio signal at a second sampling frequency; and a second area differing from the first area and storing information of the first and second sampling frequencies.
A fourth aspect of this invention is based on the third aspect thereof, and provides a digital signal recording disc wherein the first-channel digital audio signal comprises a front-channel digital audio signal and the second-channel digital audio signal comprises a rear-channel digital audio signal, and the first and second sampling frequencies are different from each other.
A fifth aspect of this invention is based on the third aspect thereof, and provides a digital signal recording disc wherein the first-channel digital audio signal comprises a front-channel digital audio signal and the second-channel digital audio signal comprises a rear-channel digital audio signal, and the first and second sampling frequencies are equal to each other, and wherein the rear-channel digital audio signal results from thinning (decimation), and the second area stores information of the thinning (the decimation).
A sixth aspect of this invention is based on the third aspect thereof, and provides a digital signal recording disc wherein the first-channel digital audio signal comprises a front-channel digital audio signal and the second-channel digital audio signal comprises a low-frequency-effect-channel digital audio signal, and the first and second sampling frequencies are equal to each other, and wherein the low-frequency-effect-channel digital audio signal results from thinning, and the second area stores information of the thinning.
A seventh aspect of this invention provides a digital signal recording disc comprising a first area storing a first-channel digital audio signal and a second-channel digital audio signal, the first-channel digital audio signal resulting from an analog-to-digital conversion of a first-channel analog audio signal at a first sampling frequency and a first quantization bit number, the second-channel digital audio signal resulting from an analog-to-digital conversion of a second-channel analog audio signal at a second sampling frequency and a second quantization bit number, the second sampling frequency differing from the first sampling frequency, the second quantization bit number differing from the first quantization bit number; and a second area differing from the first area and storing information of the first and second sampling frequencies and also information of the first and second quantization bit numbers.
An eighth aspect of this invention provides a digital signal recording disc comprising a first area storing at least first-channel and second-channel digital audio signals each assigned to either a first channel group or a second channel group, the digital audio signal in the first channel group resulting from an analog-to-digital conversion of a first analog audio signal at a first sampling frequency and a first quantization bit number, the digital audio signal in the second channel group resulting from an analog-to-digital conversion of a second analog audio signal at a second sampling frequency and a second quantization bit number; and a second area differing from the first area and storing information of the first and second sampling frequencies and information of the first and second quantization bit numbers, and also information of the assignment of the first-channel and second-channel digital audio signals to the first and second channel groups.
A ninth aspect of this invention is based on the seventh aspect thereof, and provides a digital signal recording disc wherein the first area stores left-channel and right-channel stereophonic digital audio signals, the left-channel and right-channel stereophonic digital audio signals resulting from an analog-to-digital conversion of left-channel and right-channel stereophonic analog audio signals at a third sampling frequency, and wherein the second area stores information of the third sampling frequency.
A tenth aspect of this invention is based on the seventh aspect thereof, and provides a digital signal recording disc wherein the first area stores left-channel and right-channel stereophonic digital audio signals, the left-channel and right-channel stereophonic digital audio signals resulting from an analog-to-digital conversion of left-channel and right-channel stereophonic analog audio signals at a third quantization bit number, and wherein the second area stores information of the third quantization bit number.
An eleventh aspect of this invention is based on the ninth aspect thereof, and provides a digital signal recording disc wherein the left-channel and right-channel stereophonic digital audio signals differ from the first-channel and second-channel digital audio signals, and the first area comprises a first sub area storing the first-channel and the second-channel digital audio signals and a second sub area storing the left-channel and right-channel stereophonic digital audio signals.
A twelfth aspect of this invention is based on the seventh aspect thereof, and provides a digital signal recording disc wherein the first-channel and second-channel digital audio signals result from an encoding process selected from among an AC-3 encoding process, an MPEG-1 encoding process, and an MPEG-2 encoding process.
A thirteenth aspect of this invention provides an audio-signal encoding apparatus comprising first means for quantizing a front-channel analog audio signal into a corresponding front-channel digital audio signal at a first quantization bit number; second means for quantizing a rear-channel analog audio signal into a corresponding rear-channel digital audio signal at a second quantization bit number differing from the first quantization bit number; and third means for formatting the front-channel digital audio signal, the rear-channel digital audio signal, and information of the first and second quantization bit numbers into a structure having first and second areas, the first area containing the front-channel digital audio signal and the rear-channel digital audio signal, the second area differing from the first area and containing the information of the first and second quantization bit numbers.
A fourteenth aspect of this invention provides an audio-signal encoding apparatus comprising first means for quantizing a front-channel analog audio signal into a corresponding front-channel digital audio signal at a first sampling frequency; second means for quantizing a rear-channel analog audio signal into a corresponding rear-channel digital audio signal at a second sampling frequency differing from the first sampling frequency; and third means for formatting the front-channel digital audio signal, the rear-channel digital audio signal, and information of the first and second sampling frequencies into a structure having first and second areas, the first area containing the front-channel digital audio signal and the rear-channel digital audio signal, the second area differing from the first area and containing the information of the first and second sampling frequencies.
A fifteenth aspect of this invention provides an audio-signal encoding apparatus comprising first means for quantizing a front-channel analog audio signal into a corresponding front-channel digital audio signal at a first quantization bit number and a first sampling frequency; second means for quantizing a rear-channel analog audio signal into a corresponding rear-channel digital audio signal at a second quantization bit number and a second sampling frequency, the second quantization bit number differing from the first quantization bit number, the second sampling frequency differing from the first sampling frequency; and third means for formatting the front-channel digital audio signal, the rear-channel digital audio signal, information of the first and second quantization bit numbers, and information of the first and second sampling frequencies into a structure having first and second areas, the first area containing the front-channel digital audio signal and the rear-channel digital audio signal, the second area differing from the first area and containing the information of the first and second quantization bit numbers and the information of the first and second sampling frequencies.
A sixteenth aspect of this invention provides an audio-signal encoding apparatus comprising first means for assigning each of first-channel and second-channel analog audio signals to either a first channel group or a second channel group; second means for quantizing the analog audio signal in the first channel group into a corresponding digital audio signal in the first channel group at a first sampling frequency and a first quantization bit number; third means for quantizing the analog audio signal in the second channel group into a corresponding digital audio signal in the second channel group at a second sampling frequency and a second quantization bit number; and fourth means for formatting the digital audio signals in the first and second channel groups, information of the first and second quantization bit numbers, information of the first and second sampling frequencies, and information of the assignment of the first-channel and second-channel analog audio signals to the first and second channel groups into a structure having first and second areas, the first area containing the digital audio signals of the first and second channel groups, the second area differing from the first area and containing the information of the first and second quantization bit numbers, the information of the first and second sampling frequencies, and the information of the assignment of the first-channel and second-channel analog audio signals to the first and second channel groups.
A seventeenth aspect of this invention provides an audio-signal decoding apparatus comprising first means for extracting information of a first quantization bit number for a front channel and information of a second quantization bit number for a rear channel from a reproduced signal, the second quantization bit number differing from the first quantization bit number; second means for deriving a front-channel digital audio signal and a rear-channel digital audio signal from the reproduced signal; third means for decoding the front-channel digital audio signal in response to the information of the first quantization bit number; and fourth means for decoding the rear-channel digital audio signal in response to the information of the second quantization bit number.
An eighteenth aspect of this invention provides an audio-signal decoding apparatus comprising first means for extracting information of a first sampling frequency for a front channel and information of a second sampling frequency for a rear channel from a reproduced signal, the second sampling frequency differing from the first sampling frequency; second means for deriving a front-channel digital audio signal and a rear-channel digital audio signal from the reproduced signal; third means for decoding the front-channel digital audio signal in response to the information of the first sampling frequency; and fourth means for decoding the rear-channel digital audio signal in response to the information of the second sampling frequency.
A nineteenth aspect of this invention provides an audio-signal decoding apparatus comprising first means for extracting information of a first quantization bit number and a first sampling frequency for a front channel and information of a second quantization bit number and a second sampling frequency for a rear channel from a reproduced signal, the second quantization bit number differing from the first quantization bit number, the second sampling frequency differing from the first sampling frequency; second means for deriving a front-channel digital audio signal and a rear-channel digital audio signal from the reproduced signal; third means for decoding the front-channel digital audio signal in response to the information of the first quantization bit number and the first sampling frequency; and fourth means for decoding the rear-channel digital audio signal in response to the information of the second quantization bit number and the second sampling frequency.
A twentieth aspect of this invention provides an audio-signal decoding apparatus comprising first means for extracting information of a first quantization bit number and a first sampling frequency for a first channel group and information of a second quantization bit number and a second sampling frequency for a second channel group from a reproduced signal, the second quantization bit number differing from the first quantization bit number, the second sampling frequency differing from the first sampling frequency; second means for deriving a first-channel digital audio signal and a second-channel digital audio signal from the reproduced signal, each of the derived first-channel and second-channel digital audio signals being assigned to either the first channel group or the second channel group; third means for extracting information of the assignment of the first-channel and second-channel digital audio signals to the first and second channel groups from the reproduced signal; and fourth means for decoding the first-channel digital audio signal and the second-channel digital audio signal in response to the information of the first and second quantization bit numbers, the information of the first and second sampling frequencies, and the information of the assignment of the first-channel and second-channel digital audio signals to the first and second channel groups.
A twenty-first aspect of this invention provides an optical disc player comprising first means for reproducing audio packs and control packs from an optical disc; first and second buffers; second means for alternately writing the reproduced audio packs into the first and second buffers; third means for decoding the reproduced control packs into control data; fourth means for decoding the audio packs in the first and second buffers into audio data in response to the control data; and a D/A converter for converting the audio data into an analog audio signal.
A twenty-second aspect of this invention is based on the twenty-first aspect thereof, and provides an optical disc player wherein each of the first and second buffers has a capacity of 4 kilobytes.
A twenty-third aspect of this invention is based on the eighth aspect thereof, and provides a digital signal recording disc wherein the first area stores audio data in an audio packet, and the second area stores audio data information ADI in the audio packet.
A twenty-fourth aspect of this invention is based on the eighth aspect thereof, and provides a digital signal recording disc wherein the first area comprises an audio contents block set ACBS, and the second area stores an audio-only-title audio-object attribute AOTT-AOB-ATR in audio title set information ATSI.
A twenty-fifth aspect of this invention is based on the sixteenth aspect thereof, and provides an audio-signal encoding apparatus further comprising fifth means for formatting the digital audio signals into audio data in audio packets; and sixth means for formatting the information of the first and second sampling frequencies, the information of the first and second quantization bit numbers, and the information of the assignment of the first-channel and second-channel analog audio signals to the first and second channel groups into audio data information ADI in the audio packets.
A twenty-sixth aspect of this invention is based on the sixteenth aspect thereof, and provides an audio-signal encoding apparatus further comprising fifth means for formatting the digital audio signals into an audio contents block set ACBS; and sixth means for formatting the information of the first and second sampling frequencies, the information of the first and second quantization bit numbers, and the information of the assignment of the first-channel and second-channel analog audio signals to the first and second channel groups into an audio-only-title audio-object attribute AOTT-AOB-ATR in audio title set information ATSI.
A twenty-seventh aspect of this invention is based on the twentieth aspect thereof, and provides an audio-signal decoding apparatus wherein the first means comprises means for reproducing the information of the first quantization bit number and the first sampling frequency, and the information of the second quantization bit number and the second sampling frequency from audio data information ADI in an audio packet, and wherein the third means comprises means for reproducing the information of the assignment of the first-channel and second-channel digital audio signals to the first and second channel group from the audio data information ADI in the audio packet.
A twenty-eighth aspect of this invention is based on the twentieth aspect thereof, and provides an audio-signal decoding apparatus wherein the first means comprises means for reproducing the information of the first quantization bit number and the first sampling frequency, and the information of the second quantization bit number and the second sampling frequency from an audio-only-title audio-object attribute AOTT-AOB-ATR in audio title set information ATSI, and wherein the third means comprises means for reproducing the information of the assignment of the first-channel and second-channel digital audio signals to the first and second channel group from the audio-only-title audio-object attribute AOTT-AOB-ATR in audio title set information ATSI.